Allergy, intolerance, and other adverse reactions to foods

Adverse reactions (sensitivity) to foods are categorized as either allergic (immunologic) or intolerance (nonimmunologic). Some medical conditions caused by intolerance reactions have immunologic features, but these have not adequately explained the basis of these conditions. Idiosyncratic, toxic, and anaphylactoid reactions may resemble allergic reactions clinically even though they are not based on specific immunologic events. Complaints about adverse reactions to foods are common but most cannot be reproduced by challenge studies. This fact reflects the transient nature of many of these reactions and should prompt the pediatrician to be objective when diagnosing chronic or persisting conditions. Without objectivity, dietary avoidance measures potentially can have profound nutritional and psychosocial consequences. Negative skin-prick tests with foods have a high negative predictive value to rule out IgE-mediated mechanisms being operative. Skin-prick testing with cow's milk and hydrolysate formulas is useful in distinguishing mild "topical reactors" from the more severe "systemic reactors" and in selecting "hypoallergenic" formulas for their management. However, the DBPCFC is the "gold standard" that helps distinguish between reality and strongly held erroneous beliefs. This diagnostic test has established cow's milk, egg, peanut, and soybean as the foods most commonly responsible for allergic and intolerance reactions in children. The principles of management of these food-related conditions are similar. However, each food presents unique management issues to the pediatrician.